On Sat, Nov 27, 2021 at 2:11 PM <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
>
> The patch below does not apply to the 4.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
Hi Greg,
Attaching the backport of this patch against 4.4.292 + "fuse: fix page
stealing".
The latter has been dropped from 4.4, but together with this backport
should be good to go:
stable-queue.git#c7f34b89ddfe^:queue-4.4/fuse-fix-page-stealing.patch
Thanks,
Miklos
From 753e333e86f0e41860adf34bf4ffcf10b2188b9d Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Date: Thu, 25 Nov 2021 14:05:18 +0100
Subject: [PATCH] fuse: release pipe buf after last use
Checking buf->flags should be done before the pipe_buf_release() is called
on the pipe buffer, since releasing the buffer might modify the flags.
This is exactly what page_cache_pipe_buf_release() does, and which results
in the same VM_BUG_ON_PAGE(PageLRU(page)) that the original patch was
trying to fix.
Reported-by: Justin Forbes <jmforbes@xxxxxxxxxxx>
Fixes: 712a951025c0 ("fuse: fix page stealing")
Cc: <stable@xxxxxxxxxxxxxxx> # v2.6.35
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
(cherry picked from commit 473441720c8616dfaf4451f9c7ea14f0eb5e5d65)
---
fs/fuse/dev.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 75fad41bc6e1..dc705e4be350 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -922,6 +922,11 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
return err;
}
+ page_cache_get(newpage);
+
+ if (!(buf->flags & PIPE_BUF_FLAG_LRU))
+ lru_cache_add_file(newpage);
+
/*
* Release while we have extra ref on stolen page. Otherwise
* anon_pipe_buf_release() might think the page can be reused.
@@ -929,11 +934,6 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
buf->ops->release(cs->pipe, buf);
buf->ops = NULL;
- page_cache_get(newpage);
-
- if (!(buf->flags & PIPE_BUF_FLAG_LRU))
- lru_cache_add_file(newpage);
-
err = 0;
spin_lock(&cs->req->waitq.lock);
if (test_bit(FR_ABORTED, &cs->req->flags))
--
2.31.1
